Selection of ADC. What is the meaning of VA( analog power supply)?

Thread Starter

ashokraj

Joined Feb 1, 2018
124
Hi, I am trying to find an ADC with the following specifications.
1. Power supply to it has to be less than 3V.
2. sampling frequency is 500ksps.
3. 16 bit.
4. My input signal is varying from 0 to 2V.

When I am trying to find an ADC I came across the following datasheet:
1.Datasheet-1
In it the analog power supply is mentioned as 2.7V to 5.5V, My doubt is can I supply VA with 2.7V? Vdd with 1.8V, Vref with 1.8V ?
2. what is the significance of Vref? what does it do?
3. It also has a built-in conversion clock, what does it do? My understanding is from the host/controller this IC gets the clock to interpret the signals during SPI communication.
 

ericgibbs

Joined Jan 29, 2010
16,365
hi ashok,
The info is in the d/sheet.
VA is the supply voltage.
Vref from ~0.3 to Va.
Vref sets the Voltage at which the maximum 65535 - 0xFFFF is output.

It also has a built-in conversion clock, what does it do?

The IC does not require an external clock for the A2D conversion process, its built in.

E

Added Table image.
 

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Thread Starter

ashokraj

Joined Feb 1, 2018
124
hi ashok,
The info is in the d/sheet.
VA is the supply voltage.
Vref from ~0.3 to Va.
Vref sets the Voltage at which the maximum 65535 - 0xFFFF is output.

It also has a built-in conversion clock, what does it do?

The IC does not require an external clock for the A2D conversion process, its built in.

E

Added Table image.
If there is no built-in clock do I have to use a crystal oscillator?
 

ericgibbs

Joined Jan 29, 2010
16,365
hi a,

You do not need a Crystal for the ADC.
SDO, SDI and SCLK are connections to the MCU.
E
Post your circuit diagram,:)

The MCU is the Master, so it generates the SPI data SCLK
The ADC is the Slave
 

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